Self-opening cans



United States Patent 3,409,166 SELF-OPENING CANS Leonard Thomas La Croce, Paramus, and Raymond Luscombe Batchelar, Westwood, N.J., assignors to American Can Company, New York, N.Y., a corporation of New Jersey Filed Mar. 17, 1967, Ser. No. 624,051

7 Claims. (Cl. 22054) ABSTRACT OF THE DISCLOSURE An end closure with a large removable area defined by a score line close to the periphery of the central panel and an opening tab riveted to the removable section at a point proximate to the score line has a countersink wall with an inwardly extending step the shoulder of which is level with or above the top of the portion of the tab lying close to the score line to obviate interference between a seaming chuck and the tab during an end seaming operation to thereby preclude the necessity of using a thin walled chuck to seam the end closure to a can body and to make fora more durable and shock-resistant container.

Background of the invention One of the more important recent developments in the can making industry is the trend toward scored selfopening cans which can be opened by means of an opentab which is secured to the can. The most common form of such a can is the beer and beverage can in which the product is dispensed through a comparatively small hole which is opened in the can end when the opening tab is lifted to tear away a small removable section which is defined by a score line in the end panel.

Another form is the full-open can in which a circular score line is formed proximate to the periphery of the end panel to permit its complete removal. Such full-open cans are suitable for use in the packaging of solid or chunky products such as processed or frozen vegetables and fruits, and frozen juices which are to be removed firom the container in their entirety. They are also desirable for the packaging of products which are customarily removed by insertion of the hand or a spoon or measuring cup into the container. Examples of such products are candy, shelled nut meats and coifee. Heretofore, in one form of such full-open can, the removable section has been defined by impressing the circular score line closely adjacent to the junction between the end panel and the countersink wall of the adjacent end seam and the opening tab has been secured to the removable section at a point thereon which is close to the score line so that the user can pull upwardly on the opening tab to exert a force at or near the score line to initiate a breaking out of the removable section. Insuch cans, the countersink wall is straight and rises substantially vertically from the end panel.

' Such a design has several inherent disadvantages. For one, the end closure must be sea-med to the can body with a thin walled chuck, that is, with a chuck having a wall thin enough to pass between the opening tab and the countersink wall. A thin walled chuck is undesirable because it has a proclivity to break or crack and thereby result in excessive down time. The tendency of a chuck to fail can be made less pronounced by designing the chuck with a wall which is thin only in the area which fits between the lift tab and the countersink wall. During the seaming operation, however, such a chuck must be indexed with relation to the end closure so that the lift tab will lie behind the thin wall portion of the chuck. An indexing operation limits the ultimate speed of production ice and creates a propensity for the seaming apparatus to jam from time to time.

Another disadvantage inherent in such an end closure is that during the seaming operation, the chuck bears down on the removable section so that inadvertent prema ture tearing of the score line is an ever present possibility.

Still another disadvantage of such an end closure is that an axial force exerted on the top of the countersink wall, as for example, during storage or shipment, is likely to cause tearing of the score line because such a force is transmitted down the straight countersink wall to the end panel and rupture is likely at the score line because it represents a location on the end panel which is close to the countersink wall and has a small section modulus.

All of the above-discussed disadvantages are overcome by the instant invention.

It is an object of the present invention to provide an end closure in which virtually all of the end panel can be removed without the use of an opening tool and which can be seamed onto a container body without the use of a thin walled chuck.

It is another object of the present invention to provide such an end closure which can be seamed onto the end of a container body without having the seaming chuck bear down on the removable portion.

It is still another object of the present invention to provide such an end closure which can withstand axial forces on the top of the countersink wall without tearing at the score line.

Summary of the invention According to the present invention, there is provided for a container an end closure having a central panel with a removable section defined by a score line located close to the periphery of the panel, an opening tab secured to the panel adjacent to the score line, an outwardly extend: wardly from the periphery of the panel to the flange, the countersink wall including a stepped portion comprising an inwardly extending shoulder and a downwardly extending annular flange, and a countersink wall extending uping wall portion which extends between the shoulder and the central panel, the shoulder being higher than the portion of thetab which is adjacent to the countersink wall.

Brief description of the drawing FIG. 1 is a plan view of an end closure made in accordance with the present invention;

FIG. 2 is an enlarged front elevational view taken partly in section along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged front elevational view partly in section showing the end closure of FIG. 1 just prior to being seamed onto a can body; and

FIG. 4 is an enlarged front elevational view broken away showing partly in section the area .adjacent to the end seam after the end closure has been seamed onto a can body.

Description of the preferred embodiment There is shown in FIG. 1 a plan view of an end closure indicated generally as 10 having a central panel 12 with a large removable section defined by a circular score line 14 which is positioned close to the periphery of the end panel. The closure is designed so that the removable section may be easily removed from the remainder of the end closure when it is seamed onto a can body. To this end, an opening tab 15 is secured to the end panel 12 by means of a hollow rivet indicated generally as 16 which is formed in and integral with the end panel 12. The rivet 16 has a more or less vertical annular shank 18 and an upper transverse wall 20 which is surrounded by the annular bead 22 which bears down on the pull tab to secure it to the end panel 12.

The opening tab 15 includes a handle portion 25 including an upturned end 27 which permits the handle portion 25 to be readily engaged by one or more fingers of the user. Extending outwardly from the handle portion 27 are elongated hem portions 29' which enclose a web 30. A U-shaped slit 32 in the web defines a rivet plate 34 which is engaged on its upper surface by the annular bead 22 of the rivet 16 so as to be held against the end panel 12.

The end portion 36 of the web lies outside of the U-shaped slit and adjacent to the score line 14 so that when the handle portion 25 is lifted upwardly by a user a fold develops between the ends of the U-shaped slit as the rivet plate is held against the end closure 12 and the elongated hem portions 29 and the integral end portion 36 of the web 30 are forced downwardly to rupture the score 14 and initiate the breaking out of the removable section defined by the score line. After this initial breakout is elfected, the handle 27 is pulled upwardly and to the left to completely separate the removable section defined by the score line 14 from the end closure 10.

An annular countersink wall indicated generally as 40 extends generally upwardly from the end panel 12 at a location just outside of the score line 14. The countersink wall 40 features an annular step 42 which includes a shoulder 44 which is at substantially the same level or higher than the portion of the pull tab which is ad jacent to the countersink wall 40. The step 42 separates the upper countersink wall 46 from the lower countersink wall 48. The lower countersink wall 48 is disposed inwardly of the upper countersink Wall 46 which latter merges into an outwardly extending curled flange 50 which is adapted to be formed into a part of an end seam when the end closure 10 is seamed onto a can body.

The advantage of providing the step 42 in the countersink wall 40 with the shoulder 44 at substantially the same level or at a level higher than the top of the portion of the pull tab 15 which is adjacent to the countersink wall 40 can be best explained with reference to FIG, 3 which shows the end closure 10 just prior to being seamed onto a can body indicated generally as 51. The can body 51 includes an annular outwardly extending flange 52, a side wall 54, a bottom end (not shown) and an annular bead 56 which is spaced slightly below the score 14 and is provided so that when the users hand is extended into the can after being opened, it will be directed away from the raw edge created by the tearing of the score 14.

The end closure 10 and can body 51 are seamed together by a seaming roll 58 and a chuck 60. As seen in FIG. 3, during the end seaming operation the chuck 60 is moved downwardly only far enough for its peripheral lower edge 61 to engage the step 42 of the shoulder 44. The peripheral edge 61 corresponds in diameter to the shoulder 44, and since the shoulder 44 is at substantially the same level or at a level higher than that of any part of the pull tab 15 which is adjacent to the countersink wall 40, it functionsas a stop to insure that the chuck 60 will not bear down upon the pull tab 15 or end panel 12 to create the possibility of inadvertent rupture of the score 14. It is preferable to have the shoulder 44 positioned slightly above the upper surface of the pull tab 15 to prevent contact between the chuck 60 and the pull tab. It is obvious that one advantage of this construction is that a thin walled chuck will not be required to perform the end forming operation because no part of the chuck 60 need extend into the space 62 between the opening tab and the countersink wall 40. A central recess 64 is provided in the chuck 60 to provide clearance for the upturned end 27 of the pull tab 15. Because the upturned end 27 is close to the center of the end panel 12, the recess 64 can be centrally located in the chuck 60 so as to preclude the necessity of indexing the end closure '10 and associated pull tab 15 with respect to the chuck 60 prior to the end seaming operation.

In FIG. 4 the arrangement of parts of the completed can in the area adjacent to the endseam S is shown. As pointed'out above placement of a score line on an end panel adjacent to a countersink wall makes, the score susceptible to inadvertent tearing during storage or shipment because an axial forceexerted, at the top of the countersinkwall may be transmitted to the end panel and the score line represents a line of low section modulus on the end panel which is close to the countersink wall. Because of the step 42 in the present end closure, any downward axial force exerted on the top of the countersink wall 40 will be largely dissipated before reaching the end panel 12 in the vicinity of the score line due to flexure in the area of the step 42. Thus, the present container has enhanced durability by virtue of the step 42in the end closure 12.

It is to be understood that the foregoing describes but one embodiment of the present invention, that additions, deletions and modifications may be made thereto without departing from the principles of the present invention as defined in the following claims.

We claim:

1. An end closure for a container, said end closure comprising a central panel, a score line adjacent to the periphery of said panel, an opening tab secured to said panel adjacent to said score line, a countersink wall extending upwardly from the periphery of said panel, and a flange extending outwardly from the top of said countersink wall, said countersink wall including an annular shoulder which is at least as far from said central panel as is the top of the portion of said tab which is close to said countersink wall, said shoulder dividing said countersink wall into an upper countersink wall and a lower countersink wall.

2. The end closure defined in claim 1 wherein said lower countersink wall is positioned inwardly of said upper countersink wall.

3. The end closure defined in claim 2 wherein said shoulder portion is a smooth contour between said upper countersink wall and said lower countersink wall.

4. A container comprising a can body and an end closure secured to said can body in an end seam, said end closure comprising a central panel, a score line adjacent to the periphery of said panel, an opening tab secured to said panel adjacent to said score line, a countersink wall extending upwardly from the periphery of said panel and into said end seam, said countersink wall including a shoulder which is at least as far above said panel as is the portion of said tab which is close to said countersink wall, said'shoulder dividing said countersink wall into an upper countersink wall and a lower countersink wall, said lower countersink wall positioned inwardly of said upper countersink wall.

5. The container defined in claim 4 wherein said shoulder is a smooth contour between said upper countersink wall and said lower countersink wall.

6. The end closure defined in claim 1 wherein said shoulder extends outwardly and upwardly from said lower countersink wall to said upper countersink wall.

7. The container defined in claim 4 wherein said shoulder extends upwardly and outwardly from said lower countersink wall to said upper countersink wall.

References Cited UNITED STATES I PATENTS 5/1943 Erb 22048 ,5/1967 Khoury 22054 

